The proposed clinical trial shall address whether aspirin has utility in the prevention of lung adenocarcinoma. It is a phase IIb randomized placebo controlled, double blind trial of aspirin 100 mg per day given for 1 year to current and former smokers participating in helical CT screening trials at the European Institute of Oncology in Milan, Italy. The goal is to determine if low dose aspirin affects the size of non-solid or partially solid persistent lung nodules identified by CT, since a subset of these nodules represent precursors to lung cancer. The clinical trial shall be performed at the European Institute of Oncology, with monitoring and oversight provided by MD Anderson.